QBism.org

As promised, my paper comparing QBism and Rovelli’s relational interpretation of quantum mechanics (RQM) is finally on the arXiv; you can upvote it or comment on it on Scirate.

One of the things that made this paper tricky to write was trying to explain how QBism can talk about “reality without agents” and yet at the same time keep insisting that this is not the same as Rovelli’s conception of reality. Paraphrasing myself, here’s how I tried to explain it in a recent email to Carlo Rovelli and Andrea Di Biagio:

QBists reject the doctrine of ‘physicalism’, which says that the elements of the ontology have a “purely mechanical” or “purely physical” nature. We think there is more to the “stuff of the universe” than just material mechanisms, even objectively probabilistic ones. At the risk of being misinterpreted, I’d say the sentiment is that there is a certain “liveliness” to the stuff of the universe, although what precise form this is supposed to take in a QBist ontology is still unclear. Ultimately it is this metaphysical commitment against physicalism that really drives the deepest wedge between QBism and RQM.

No doubt our critics won’t be satisfied with that. In this day and age when you’re supposed to publish 5 papers a year of groundbreaking new research, it is frowned upon to say “we don’t know yet”. The fact is for the past year at least we have been discussing this very topic with philosophers, hotly debating it in our online group discussions, and trying to work out a more precise answer. Until then, we all just have to savour that good old feeling of not knowing, which is the spice of all science.